Fix #1864: xunit missing output with --reporter-options output

[danielstjules]

Fix for #1864

./bin/mocha --reporter=xunit --reporter-options output=results.xml test.js; cat results.xml
<testsuite name="Mocha Tests" tests="2" failures="1" errors="1" skipped="0" timestamp="Wed, 09 Sep 2015 19:34:48 GMT" time="0.004">
<testcase classname="my test" name="should pass" time="0.001"/>
<testcase classname="my test" name="should fail" time="0.001"><failure><![CDATA[fail
Error: fail
    at Context.&lt;anonymous&gt; (test.js:7:14)
    at callFnAsync (/Users/danielstjules/git/mocha/lib/runnable.js:306:8)
    at Test.Runnable.run (/Users/danielstjules/git/mocha/lib/runnable.js:261:7)
    at Runner.runTest (/Users/danielstjules/git/mocha/lib/runner.js:417:10)
    at /Users/danielstjules/git/mocha/lib/runner.js:524:12
    at next (/Users/danielstjules/git/mocha/lib/runner.js:338:14)
    at /Users/danielstjules/git/mocha/lib/runner.js:348:7
    at next (/Users/danielstjules/git/mocha/lib/runner.js:281:14)
    at Object._onImmediate (/Users/danielstjules/git/mocha/lib/runner.js:316:5)]]></failure></testcase>
</testsuite>

[danielstjules]

Merging this in since the build is green, and it's essentially a 1 line fix (just moving inherits)